1. Field of the Invention
The invention relates to an ejector pump with a nozzle arranged upstream of a mixing tube and with holding elements for aligning the nozzle with respect to the mixing tube, the nozzle and the mixing tube being produced from plastic by the injection-molding process.
2. Description Of The Prior Art
Ejector pumps of the above type are often used in fuel tanks of modern motor vehicles and are therefore known. The ejector pumps are usually used for filling a surge chamber arranged in the fuel tank or, in the case of a multi-chamber tank, for delivering fuel from one chamber to the other chamber. In the production of the known ejector pump from fuel-resistant plastic, the mixing tube and the nozzle are produced in separate molds, for example by the injection-molding process, and are subsequently adhesively bonded to each other. The holding elements are in this case shaped as webs fastened integrally to the nozzle and, after fitting of the ejector pump, are supported on corresponding surfaces of the mixing tube.
A disadvantage of the known ejector pump is that the nozzle and the mixing tube each have tolerances and therefore can only be aligned with each other with great difficulty. However, misalignment of the nozzle with respect to the mixing tube leads to a great reduction in the efficiency of the ejector pump.
The invention is based on the problem of designing an ejector pump of the type stated at the beginning in such a way that it has particularly high efficiency and can be produced at low cost.
This problem is solved according to the invention by the nozzle and the mixing tube being shaped in a common mold for production as an interconnected component.
This shaping has the effect that the nozzle and the mixing tube are aligned exactly in relation to each other after they are removed from the mold. As a result, the ejector pump has particularly high efficiency. Since all the main components of the ejector pump according to the invention are produced integrally, there is likewise no reduction in its efficiency as a result of defective assembly. By being produced in a single mold, the ejector pump can also be produced at particularly low cost. A further advantage of this shaping is that the ejector pump according to the invention has high stability and therefore holding forces in the fuel tank do not lead to a reduction in its efficiency.
A simultaneous alignment and fastening of the ejector pump according to the invention, intended for the delivery of fuel into a surge chamber of a motor vehicle, can be achieved in a simple way if it has means for bracing it in a delivery unit or a surge chamber arranged in a fuel tank of a motor vehicle. This has the effect of greatly simplifying the fitting of the ejector pump in the delivery unit. A further advantage of this ejector pump braced in the delivery unit is that the delivery unit is of a very compact construction and can be put together in a modular manner to form a preassemblable unit.
The connection of the ejector pump according to the invention to a fuel line is particularly simple in design terms if the nozzle has on its side facing away from the mixing tube a sealing flange and means for bracing it with a correspondingly shaped fuel line. For the bracing, the sealing flange of the nozzle and the fuel line may for example be screwed to each other or connected to each other by snap-in means.
It helps to simplify further the fitting of the ejector pump according to the invention if an annular sealing surface is arranged on the outer side of the mixing tube to seal off the ejector pump fitted in the delivery unit or in the surge chamber.
The ejector pump according to the invention can be easily braced in an adjacent component if snap-in means are arranged on the outer side of the mixing tube for fastening on the delivery unit or on the surge chamber.
According to another advantageous development of the invention, the snap-in means are of a particularly simple design if they take the form of snap-in hooks.
The production of the ejector pump according to the invention can be performed in a mold which allows for the most part axial demolding if the entire mixing tube is made straight or conically widening from the intake region to its free end. It goes without saying that straight sections of the mixing tube and conical sections may alternate here.
Intake openings for taking in fuel could be arranged for example in the end face of the mixing tube receiving the nozzle. The ejector pump according to the invention is of a particularly compact form, however, if the holding elements for lateral delimitation are formed by intake openings arranged in the lateral surface of the mixing tube.